Carpe Noctem - Seize the Night! Week of Oct. 16, 2006

ARCTURUS IN AUTUMN

Oh, then I knew at last that my own autumn was upon me,
I felt it in my blood,
Restless as dwindling streams that still remember
The music of their flood. There in the thickening dark a wind-bent tree above me
Loosed its last leaves in flight--
I saw you sink and vanish, pitiless Arcturus,
You will not stay to share our lengthening night.

Sara Teasdale, 1926 (TOAOAL-II, pg. 1245)

Listener Question

Dan wanted directions for finding the Andromeda galaxy! I like to start with Alpheratz (al-FEE-rahts) the corner star in the great square of Pegasus shared by both constellations. This is the corner closes to Perseus and Cassiopeia. There is a long slender "V" with the brighter of the two track further away from Cassiopeia. If you start at Alpheratz, jump two stars down the brighter track to Mirach. The jump towards Cassiopeia two stars and stop. M31, the Andromeda galaxy, is just a nudge to the east. You will have 3 galaxies right there, M31, M32 and M110.

If you are having problems with faint stars another way to find M31 is to follow Cassiopeia. Start by finding Cassiopeia, if you draw a "W" on paper from left to right you make 4 lines resulting in 2 "V"s (no vendetta here)the second "V" points straight to Mirach then just back up a quarter of the way and shift east. M31 from the city looks nothing like the pictures she huge smear in the telescope with a very bright center. Give yourself time and dark skies to improve her view.

photo courtesy of: NASA Mariner 10

Feature Attraction - Mercury

Historical/Myological Facts

• Mercury was the Roman god of trade and commerce, in the same vein as Hermes of the Greeks, the messenger
• In India Mercury was called Buddha
• Mayans charted the motion of the planet Mercury as well; records of their detailed observations are found in the Dresden Codex. These include the appearance of Mercury as a morning star in 733 B.C. and as an evening star in 727. The Mayans also calculated that Mercury would rise and set in the same place in the sky every 2,200 days
• Translations from surviving cuneiform tablets reveal that Mercury was designated by many names, including that transcribed by archaeologists as MulUDU.IDIM.GU.UD. Mercury was often associated with Nabu, or Ninurta, the god of water and writing. Later, in Akkadian, it became known as Shikhtu, meaning "jumpy"
• For the Egyptian Mercury was called Thoth, the great measurer - a divinity associated with knowledge, and the inventor of speech, writing, and arithmetic
• For the northern ancestors, Mercury was named Odin, the supreme god. Often referred to as the god of wisdom, magic, and war, and the inventor of runes, his name means "inspired one". Odin was worshiped throughout northern Europe (including Britain), wherever the Vikings and other Nordic peoples settled. Odin was also known as Woden, and it is from this form that the English word for Wednesday is derived

  450 B.C. the Greeks started studying the motions of the planets and using geometry to measure the size of the Earth, Sun and Moon. Mercury was known by two different names, associated with its evening and morning appearances. These were Apollo (god of truth, the arts, archery, plagues, and divination) and Hermes (god of writing and messenger to the other gods).

Fast Facts!

• Mercury is the nearest planet to the sun. It has the most extreme contrast in temperature between day (430°C) and night (-180°C) in the solar system. Daytime temperatures are high enough to melt zinc and tin.
• BUT! Mercury is not the hottest planet, Venus is due to its heat trapping atmosphere
• Mercury's axis of rotation is oriented nearly perpendicular to the planet's orbit (axial tilt=0), so that in the polar regions sunlight strikes the surface at a constant grazing angle. The interiors of large craters at the poles are permanently shadowed and remain perpetually cold, below -212ºC (-350° F). Amazingly, radar observations of Mercury's north pole by Arecebo(a region not mapped by Mariner 10) show evidence of water ice in the protected shadows of some craters.
• Mercury's orbit is highly eccentric; at perihelion it is only 46 million km from the Sun but at aphelion it is 70 million. 
• Pluto has the most elongated orbit, two-thirds further from the Sun at aphelion than at perihelion.
• Mercury has virtually no atmosphere, meaning life as we know it is impossible.
• Mercury rotates three times for every two orbits of the sun
• This fact and the high eccentricity of Mercury's orbit would produce very strange effects for an observer on Mercury's surface. At some longitudes the observer would see the Sun rise and then gradually increase in apparent size as it slowly moved toward the zenith. At that point the Sun would stop, briefly reverse course, and stop again before resuming its path toward the horizon and decreasing in apparent size. All the while the stars would be moving three times faster across the sky. Observers at other points on Mercury's surface would see different but equally bizarre motions.
• Mercury is the second densest major body in the solar system, after Earth. Actually Earth's density is due in part to gravitational compression; if not for this, Mercury would be denser than Earth. This indicates that Mercury's dense iron core is relatively larger than Earth's, probably comprising the majority of the planet. Mercury therefore has only a relatively thin silicate mantle and crust.
• Only one spacecraft has been to mercury, Mariner 10, passing three times in 1974-75.
• However NASA's Messenger is on the way, launched in August 2004, and will fly by three times and then enter mercury orbit in March 2011. Then in 2012, ESA/ISAS's BepiColombo will be launched, also into mercurian orbit.
• Because of mercury's proximity to the sun, it cannot safely be photographed by the Hubble Space Telescope.
• Mercurian atmosphere is thin enough to be described as an exosphere, meaning the constituent atoms never collide. The identified elements in the exosphere are sodium, potassium, hydrogen, oxygen and neon. Ions and high frequency electromagnetic radiation from the sun are responsible for dislodging the atoms in the exosphere.
• Mass (kg) 3.302x1023
• Diameter is 4,880 kilometers (3,032 miles) (32% that of Earth) 2nd smallest of the classical planets now the smallest
• Perihelion (km) 46.00x106
• Aphelion (km) 69.82x106
• Length of day (hours) 4222.6

Why care about Mercury?

It offers a chance to examine another outcome of the processes that also produced Earth, Venus and Mars.

Learning how Mercury ended up the densest planet (after correcting for internal pressures) will tell us much about planetary formation.

Discovering how Mercury has sustained a magnetic field while larger bodies either have lost an earlier field (as Mars did) or have no present field and no record of a past field (Venus) will help us to understand magnetic field generation in our own planet.

Mercury also has the thinnest atmosphere among all the terrestrial planets and an incredibly wide temperature range. In fact, temperatures vary from nearly the highest in the solar system (at the equator) to among the coldest (in the permanently shadowed areas where ice deposits seem to lurk). Documenting the nature of Mercury's tenuous and changeable atmosphere and the composition of its mysterious polar deposits - thought by many to consist of water ice - will give us new insight into the volatile materials in the inner solar system.

Transit of Mercury Nov. 8 2006

Viewing the transit safely!
Build a solar filter Sources for Baader film (http://www.baader-planetarium.com/sofifolie/details_e.htm#distributor)

Fun Mercury Tools

Planets

• Mercury - Mag 0.0 in Libra. Mark your calendars for inferior conjunction and visible transit on Nov. 8th!
• Jupiter - Mag -1.6 in Libra. Clearly visible low in the sky just after sunset. Any telescope can reveal its two widest cloud bands and four Galilean satellites.
  
  
  
  images courtesy of: Stellarium software
• Pluto - Mag +14.0 in Ophiuchus
• Uranus - Mag +5.8 in Aquarius Uranus is best seen in a dark moonless sky away from artificial lighting. It may be seen looking like a very faint star to the dark-adapted naked eye that shimmers in and out of visibility just over 1 degree east of Lambda Aquarii. Find the tipped over letter Y of Aquarius, go 4 thumbwidths southeast to find Lambda, and then look pinky nail east.
• Neptune - Mag +7.9 in Capricorn 1 degree north of the +4.3 magnitude star Iota Capricorni

Too close to the sun..

• Mars - Mag +1.6 is at the western end of Virgo. You will have to look hard in the haze of the horizon and it will help to be closer to the equator.
• Venus - Mag -3.8 in Virgo.

• Saturn - Mag +0.6 on the western edge of Leo!

• 1 Ceres +7.9 mag in Piscis Austeralis 18.5 degrees West of Formalhaut
• Eris mag +19 in central Cetus

Constellations

Circinus -Circinus was invented by Lacaille during his stay at the Cape of Good Hope between 1751 and 1752. Latin for compass, is one of the small southern (declination -50 to -60 degrees) constellations. It represents a tool used in drawing maps and as such should not be confused with Pyxis, a constellation associated with a ship's compass.

Pyxis(-Latin for box as in Pyxis Navigatum [lit. Sailor's Box, a compass]) is a minor southern constellation introduced by Nicolas Louis de Lacaille under the name Pyxis Nautica. It is perhaps supposed to represent the compass of Argo Navis but not formally a part of Argo Navis; that is, the stars in it have their own independent Bayer designations (unlike Carina, Puppis and Vela which retained and split among themselves the Bayer designations from Argo).

Vulpecula - (vul-pek-U-lu) the Fox, It was originally known as Vulpecula cum ansere = "the Fox with the Goose" created by Hevelius, but the goose no longer appears on star charts but the name remains in Alpha Vulpeculae is a red giant of spectral class M0 and has apparent magnitude +4.4 the least faint star in this very faint constellation.

However! :-) As faint as this constellation is it has too noteworthy features; "The Coathanger" more formally named Brocchi's Cluster (Collinder 399) and M27, the Dumbbell Nebula, is a large, bright planetary nebula which was discovered by the French astronomer Charles Messier in 1764 as the very first object of its kind. Find them!

Viewing

Naked eye -
NH: Time to get up early! Winter triangle, the Hyades (head of Taurus) and the Winter hexagon
SH: Large and Small Magellanic clouds, 47 Tucanae

Binocular -
NH: Star hop your way to the Andromeda Galaxy.
SH: NGC 362 globular cluster in Tucanae

Telescope -
Comet Swan currently in Canes Venatici. From the city it looks like a faint nebulous globular cluster! I did NOT see this! Aerith.net, Heavens-above.com
Comet C2006 T1 (Levy) currently in Leo. Wait until mid-week for the moon to get out of the way.
M27 - The Dumbell Nebula in Vulpecula
NH: M33 in Triangulum directly opposite Mirach from M31 - and with it NGC 604 and for a real challenge NGC 595, NGC 592 and NGC 588!
SH: Circinus Galaxy - NGC 346
in SMC -find it NGC 2070 - the Tarantula Nebula -find it Southern hemisphere challenge object very low surface brightness Mag 12.9
NGC 5715 9.8 Open Cluster

The Moon

Images created with Lunar Phase Pro

Our beautiful lunar photos are courtesy of Frank Barrett at celestialwonders.com I recommend visiting his site and checking out his lunar phase photos. You can zoom in for more detail.

Remember latitudes that are negative (-) are South and longitudes that are negative (-) are West!

Comets

Comets for the Month.

"One touch of nature makes the whole world kin"
-- Shakespeare

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Music

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The harvest moon hangs round and high
It dodges clouds high in the sky,
The stars wink down their love and mirth
The Autumn season is giving birth.
Oh, it must be October
The leaves of red bright gold and brown,
To Mother Earth come tumbling down,
The breezy nights the ghostly sights,
The eerie spooky far off sounds
Are signs that it's October.
The pumpkins yellow, big and round
Are carried by costumed clumsy clowns
It's Halloween - let's celebrate.

- Pearl N. Sorrels, It Must be October

Great site for sunrise and sunset times and a downloadable toolbar application by Steve Edwards

Download this month's sky map!

Northern hemisphere sky map
Southern hemisphere sky map

Also visit James Barclay's site for a great tour of the Southern Hemisphere October sky.

Key Dates for October

Days and Times in UT (help with time)

Astronomical

Historical

Events

Earth's major motions for 2006

Perihelion		Jan 4
Equinox		Mar 20 18:26(UT)
Solstice		June 21 12:26(UT)
Aphelion		July 3
Equinox		Sept 23 04:03(UT)
Solstice		Dec 22 00:22(UT)

Planet Positions for 2006

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Venus

Sgr

Sgr

Cap

Aqr

Psc

Ari

Tau

Cnc

Leo

Vir

Lib

Sgr

Mars

Ari

Tau

Tau

Gem

Gem

Cnc

Leo

Leo

Vir

Vir

Lib

Sco

Jupiter

Lib

Lib

Lib

Lib

Lib

Lib

Lib

Lib

Lib

Lib

Lib

Sco

Saturn

Cnc

Cnc

Cnc

Cnc

Cnc

Cnc

Cnc

Leo

Leo

Leo

Leo

Leo

Comets for October

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Music Scottish Guitar Quartet -"Near the Circle"
Mark Heimonen - "Celebration"
I Awake - "New Time Nomads"